Image display devices are being widely used in a variety of applications, including TV screens, monitors of personal computers, etc. The plasma display panel (PDP) is gaining popularity as a next-generation display device to replace the CRT because a PDP is thin and a large screen can be readily fabricated with a plurality of units. A PDP includes a plasma display panel on which an image is displayed using a gas discharge phenomenon, and exhibits superior display capabilities, including high display capacity, high brightness, high contrast, clear latent image, a wide viewing angle, etc. In a PDP apparatus, when a direct current (DC) or alternating current (AC) voltage is applied to electrodes, a discharge of gas plasma is created, resulting in the emission of ultraviolet (UV) light. The UV emission excites adjacent phosphor materials, resulting in electromagnetic emission of visible light. Despite the above advantages, PDPs face several challenges associated with driving characteristics, including an increase in electromagnetic wave radiation, near-infrared emission, and phosphor surface reflection, and an obscured color purity due to orange light emitted from helium (He), neon, or xenon (Xe) used as a sealing gas.
Some believe that the electromagnetic waves and near-infrared rays generated in PDPs may adversely affect human bodies and cause malfunctions of precision machines such as wireless telephones or remote controllers (e.g., see U.S. 2006/0083938, incorporated herein by reference). These waves, taken individually or collectively, may be referred to as electromagnetic interference (EMI). Thus, in order to make use of such PDPs, there is a desire to reduce the electromagnetic waves and near-infrared (IR or NIR) rays emitted from the PDPs to a predetermined level or less. In this respect, various PDP filters have been proposed for shielding electromagnetic waves or near-infrared rays emitted from the PDPs, reducing reflection of light and/or enhancing color purity. The proposed PDP filters are also required to meet transmittance requirements because the filters are installed on a front surface of each of the PDPs.
In order to reduce the electromagnetic waves and NIR waves emitted from plasma display panels to a predetermined level or less, various PDP filters have been used for the purposes of, for example, shielding electromagnetic waves or NIR emitted from the PDPs, reducing reflection of light and/or enhancing color purity. High transmittance is required for such filters because they are generally applied to the front surface of PDPs. Typical electromagnetic wave shielding filters meeting such requirements and characteristics are classified into a metal mesh-pattern filter and a transparent conductive film filter. Although the metal mesh-pattern filter exhibits a good electromagnetic wave shielding effect, it has several disadvantages including poor transmittance, image distortion, and an increase in the production cost due to a costly mesh. Due to such disadvantages, electromagnetic wave shielding filters using transparent conductive films are being widely used instead of the metal mesh-pattern filter. The transparent conductive film is generally formed of a multi-level thin film structure in which a metal film and a high-refractive-index transparent thin layer are sandwiched. Silver or a silver-based alloy may be used as the metal film. However, conventional PDP EMI filters tend to lack durability and/or can stand to be improved upon with respect to visible transmission and/or shielding properties.
Moreover, certain PDP EMI filters need to be heat treated (e.g., thermally tempered). Such heat treatment typically requires the use of temperature(s) of at least 580 degrees C., more preferably of at least about 600 degrees C. and still more preferably of at least 620 degrees C. The terms “heat treatment” and “heat treating” as used herein mean heating the article to a temperature sufficient to achieve thermal tempering and/or heat strengthening of the glass inclusive article. This definition includes, for example, heating a coated article in an oven or furnace at a temperature of at least about 550 degrees C., more preferably at least about 580 degrees C., more preferably at least about 600 degrees C., more preferably at least about 620 degrees C., for a sufficient period to allow tempering and/or heat strengthening. In general, heat treating may be accomplished at temperatures of about 550 degrees C. to about 650 degrees C. In certain instances, the HT may be for at least about 4 or 5 minutes. The use of such high temperatures (e.g., for 5-10 minutes or more) often causes coatings to break down and/or causes one or more of the aforesaid desirable characteristics to significantly deteriorate in an undesirable manner. Conventional PDP EMI filters tend to suffer from a lack of thermal stability and/or durability upon heat treatment (HT). In particular, heat treatment tends to cause conventional PDP filters to break down.
In view of the above, there exists a need in the art for an improved PDP filter which is improved (with respect to conventional PDP EMI filters) with respect to one or more of: (i) improved chemical durability, (ii) improved thermal stability (e.g., upon optional heat treatment such as tempering), (iii) improved visible transmission, and/or (iv) improved EMI shielding properties.
To overcome these and/or other disadvantages, attempts have been made by the assignee of the instant invention to use a transparent conductive coating (TCC) as an EMI filter as described, for example, in Application Ser. No. 61/071,936, the entire contents of which are hereby incorporated herein by reference. FIGS. 14(a)-14(c) provide an example view of how a PDP filter may be arranged with reference to a front cover glass. More particularly, FIG. 14(a) is a cross sectional view of the EMI filter, front cover glass, and black and silver frit frames for use at the front of a PDP panel, FIG. 14(b) is a front or viewer's view of the EMI filter and black frit frame for use at the front of a PDP panel, and FIG. 14(c) is a rear or plasma view of the EMI filter and black and silver frit frames for use at the front of a PDP panel. As shown in these figures, a front cover glass 142 is provided. Black frit 144 and silver frit 146 are applied to the front cover glass 142 on the major surface thereof opposite the viewer, and they form the frames shown in FIGS. 14(b) and 14(c). Thus, the black frit 144 is visible from the viewer's side of the of the PDP panel, whereas the silver frit 146 is substantially hidden from the viewer's side of the PDP panel, as shown in FIG. 14(b). By contrast, both the silver frit 146 and the black frit 144 are visible from the plasma side of the PDP panel, as shown in FIG. 14(c), because of how and where the silver frit 146 is applied in relation to the black frit 144. As will be appreciated from FIGS. 14(b) and 14(c), the black frit 144 and the silver frit 146 are both provided around the periphery of the glass substrate 142, although the black frit 144 extends around and/or helps to conceal the silver frit 146 when viewed from the viewer's side, as shown in FIG. 14(b). In other words, the black frit 144 and the silver frit 146 frame the portion of the coated glass substrate 140, with the black frit 144 being the “inner mat” and the silver frit 146 being the “outer mat” when viewed from the plasma's side shown in FIG. 14(c). By comparison, the “single mat” visible from the viewer's side is the black frit 144. It will be appreciated that in some instances at least some black frit material may be visible “outside” the silver frit 146, but its presence generally is not a problem since the bezel or frame of the plasma display device typically conceals such areas, anyway.
In practice, the assembly shown in the FIG. 14 embodiment is made as follows. A front cover glass 142 is provided. It is coated with black frit 144 and silver frit 146 and cut to a predetermined size appropriate for the PDP in which it will be housed (e.g., such that the visible area 140 has a 42″, 48″, 50″, 55″, or larger or smaller diagonal dimension). The front cover glass 142 may be cut and then coated with black frit 144 and silver frit 146. The assembly including the front cover glass 142, black frit 144, and silver frit 146 is then fired and/or tempered. The TCC 148 finally is applied to the cut, fired/tempered assembly, typically via sputter coating or the like. Ultimately, a visible area 140 that is coated with TCC 148 will be framed by the black frit 144 and silver frit 146. It is noted that in this technique, the TCC 148 is applied over the black frit 144 and silver frit 146 such that, when ultimately assembled into a plasma display device, it will be the closest layer to the plasma television portion of assembly.
In view of the description provided above, it will be appreciated that the TCC 148 is applied after any kind of heat treatment and after the silver and black frits are applied. Furthermore, because the glass substrate 142 is cut to the appropriate predetermined size, it must be coated at this size. In other words, the TCC 148 is applied after the glass substrate 142 is cut to an appropriate size.
Although this process has been successful in producing high-quality PDPs and thus high-quality plasma display devices, further improvements are still possible and desirable. For example, the process described above often leads to a significant amount of waste and/or presents challenges when the TCC is applied. The assembly lines that provide the TCC coatings (e.g., sputtering assembly lines) typically are configured to accommodate stock, non-cut sheets that fit substantially the entire “bed size” of a conveyor. Unfortunately, the above-described process requires coating cut glass sheets. These cut glass sheets do not occupy the full dimensions of a typical conveyor or bed size, which leads to at least some of the problems noted below and/or presents other challenges.
To increase the yield of the coating process, various cut glass sheets may be arranged on the conveyor in close relative proximity to one another in order to attempt to fill up the area on the conveyor. In other words, cut glass sheets may be placed on a conveyor so as to approximate a large, un-cut glass sheet that would otherwise occupy substantially the entire bed size of the conveyor. Unfortunately, this compromise approach often takes time and/or significant manual effort, related at least in part to the careful arrangement of the cut glass sheets. Even with the attempted maximization of space, sputtered material is often wasted. Additionally, because the sheets oftentimes are small compared to bulk non-cut sheets, some sizes cannot be coated at all, while others inadvertently fall through rollers provided on the assembly line or are otherwise damaged or destroyed during the coating process.
Thus, it will be appreciated that there is a need in the art for improved PDPs, and/or improved PDP manufacturing techniques.
In certain example embodiments of this invention, a plasma display panel (PDP) includes a filter supported by a glass substrate for blocking/shielding substantial amounts of electromagnetic waves, with the filter being supported by a side of the substrate opposite a viewer. A black frit and a silver frit comprise a filter frame and are supported by the filter such that the filter is closer to the glass substrate than either or both of the frits. The filter has high visible transmission, and is capable of blocking/shielding electromagnetic waves. In certain example embodiments, a silver based coating of the EMI filter reduces damage from EMI radiation through highly conductive Ag layers, blocks significant amounts of NIR and IR radiation from outdoor sunlight to reduce PDP panel temperature, and enhances contrast ratio through reduced reflection, while maintaining high visible transmission. In certain example embodiments, the filter is a TCC filter. Advantageously, a TCC may be coated on a stock, non-cut glass sheet.
In certain example embodiments, a plasma display device is provided. A plasma display panel is provided. An electromagnetic interference (EMI) filter is provided at a front portion of the plasma display panel. The EMI filter includes a multi-layer silver-inclusive transparent conductive coating (TCC) supported by an inner surface of a glass substrate. An inner black frit frame is disposed around a portion of the glass substrate that corresponds to a visible portion of the plasma display panel. An outer silver frit frame is disposed around the inner black frit frame at the periphery of the glass substrate. The TCC is provided closer to the glass substrate than the inner and outer frit frames.
In certain example embodiments, a method of making a plasma display device including a plasma display panel and an electromagnetic interference (EMI) filter provided at a front portion of the plasma display panel is provided. A glass substrate is provided. A multi-layer silver-inclusive transparent conductive coating (TCC) is sputter coated on an inner surface of the substrate. After the sputter-coating of the TCC, the substrate is cut to a predetermined. An inner black frit frame is applied around a portion of the glass substrate that corresponds to a visible portion of the plasma display panel. An outer silver frit frame is applied around the inner black frit frame such that the outer silver frit frame will be located at the periphery of the cut glass substrate. At least one high-temperature treatment is performed. The at least one high-temperature treatment heat treats the cut substrate and melts together the black and silver frit frames. The TCC is provided closer to the glass substrate than the inner and outer frit frames.
In certain example embodiments, a method of making an electromagnetic interference (EMI) filter for a plasma display device is provided. A glass substrate is provided. A multi-layer silver-inclusive transparent conductive coating (TCC) is sputter coated on an inner surface of the substrate. After the sputter-coating of the TCC, the substrate is cut to a predetermined. An inner black frit frame is applied around a portion of the glass substrate that corresponds to a visible portion of the plasma display panel. An outer silver frit frame is applied around the inner black frit frame such that the outer silver frit frame will be located at the periphery of the cut glass substrate. At least one high-temperature treatment is performed. The at least one high-temperature treatment heat treats the cut substrate and melts together the black and silver frit frames. The TCC is provided closer to the glass substrate than the inner and outer frit frames.
In certain example embodiments, an electromagnetic interference (EMI) filter for use with a plasma display panel of a plasma display device is provided. A multi-layer silver-inclusive transparent conductive coating (TCC) is supported by an inner surface of a glass substrate. An inner black frit frame is disposed around a portion of the glass substrate that corresponds to a visible portion of the plasma display panel. An outer silver frit frame is disposed around the inner black frit frame at the periphery of the glass substrate. The TCC is provided closer to the glass substrate than the inner and outer frit frames.
In certain example embodiments, a method of making a plasma display device including a plasma display panel and an electromagnetic interference (EMI) filter provided at a front portion of the plasma display panel is provided. A glass substrate is provided. The glass substrate includes a sputter deposited multi-layer silver-inclusive transparent conductive coating (TCC) on an inner surface thereof. The glass substrate has been cut to a predetermined size following the sputter depositing of the TCC. An inner black frit frame is applied around a portion of the glass substrate that corresponds to a visible portion of the plasma display panel. An outer silver frit frame is applied around the inner black frit frame such that the outer silver frit frame will be located at the periphery of the cut glass substrate. At least one high-temperature treatment is performed. The at least one high-temperature treatment heat treats the cut substrate and melts together the black and silver frit frames. The TCC is provided closer to the glass substrate than the inner and outer frit frames. The inner black frit frame is non-conductive and the outer silver frit frame is conductive.
In certain example embodiments, a plasma display device is provided. A plasma display panel is provided. An electromagnetic interference (EMI) filter is provided at a front portion of the plasma display panel. The EMI filter includes a multi-layer silver-inclusive transparent conductive coating (TCC) supported by an inner surface of a glass substrate. A conductive black frit frame is disposed around the periphery of the glass substrate. The TCC is provided closer to the glass substrate than the conductive black frit frame.
In certain example embodiments, a method of making a plasma display device including a plasma display panel and an electromagnetic interference (EMI) filter provided at a front portion of the plasma display panel is provided. A glass substrate is provided. The glass substrate includes a sputter deposited multi-layer silver-inclusive transparent conductive coating (TCC) on an inner surface thereof. The glass substrate has been cut to a predetermined size following the sputter depositing of the TCC. A conductive black frit frame is applied around the periphery of the cut glass substrate. At least one high-temperature treatment is performed. The at least one high-temperature treatment heat treats the cut substrate and firing the conductive black frit frame. The TCC is provided closer to the glass substrate than the conductive black frit frames.
As noted above, when using a TCC, a conductive peripheral frame layer (frit) may be screen printed either on the bare glass substrate prior to TCC coating or on the coated glass substrate. Indeed, as shown in and described in connection with FIG. 16 below, the conductive buss bar makes contact with the metal frame of the television (e.g., through conductive tape, etc.). In certain current techniques used successfully by the assignee of the instant invention, the conductive buss bar comprises either a silver frit or a layered combination of a conductive silver frit and a non-conductive black frit (e.g., to produce a more aesthetically pleasing product). Unfortunately, however, the screen printing of the conductive frit on the glass adds process steps, increases manufacturing costs, and reduces manufacturing yield, e.g., for the reason described above. Furthermore, although the use of a conductive black frit has been successfully implemented by the assignee of the instant invention, further improvements are still possible. Indeed, it will be appreciated that the desire to reduce the cost of components in a plasma television is ongoing, and that one particular target for cost reduction involves yet further reductions in costs related to EMI filters.
In certain example embodiments of this invention, there is provided a plasma display device comprising a plasma display panel (PDP); and an electromagnetic interference (EMI) filter provided at a front portion of the plasma display panel. The EMI filter includes an EMI coating supported by a glass substrate, with the EMI coating including the following layers moving away from the glass substrate: a first high index layer having a refractive index (n) of at least about 2.2; a first layer comprising silicon nitride; a first layer comprising zinc oxide; a first EMI shielding layer comprising silver contacting the first layer comprising zinc oxide; a first layer comprising an oxide of Ni and/or Cr contacting the first EMI shielding layer comprising silver; a first metal oxide layer; a second layer of silicon nitride; a second layer comprising zinc oxide; a second EMI shielding layer comprising silver contacting the second layer comprising zinc oxide; a second layer comprising an oxide of Ni and/or Cr contacting the second EMI shielding layer comprising silver; a second metal oxide layer; a third layer of silicon nitride; a third layer comprising zinc oxide; a third EMI shielding layer comprising silver contacting the third layer comprising zinc oxide; a third layer comprising an oxide of Ni and/or Cr contacting the third EMI shielding layer comprising silver; and an overcoat layer comprising a transparent conducting oxide (TCO). The EMI filter has a sheet resistance of less than about 1 ohm.
In certain example embodiments of this invention, there is provided a plasma display device comprising a plasma display panel (PDP) and an electromagnetic interference (EMI) filter provided in direct electric contact with a front portion of the plasma display panel. The EMI filter includes an EMI coating supported by a glass substrate, with the EMI coating including the following layers moving away from the glass substrate: an anti-reflective coating; a first dielectric layer; a first EMI shielding layer comprising silver; a second dielectric layer; a second EMI shielding layer comprising silver; a third dielectric layer; a third EMI shielding layer comprising silver; a fourth dielectric layer; a fourth EMI shielding layer comprising silver; and an overcoat layer comprising a transparent conducting oxide (TCO). The glass substrate and the EMI coating combined have a visible transmission of at least about 60%. The EMI filter has a sheet resistance of less than about 0.9 ohm. The TCO has a refractive index of about 1.95-2.05.
In certain example embodiments of this invention, there is provided an EMI filter for a plasma display device comprising an EMI coating supported by a glass substrate. The EMI coating includes the following layers moving away from the glass substrate: a first high refractive index layer; a first layer comprising silicon nitride; a first layer comprising zinc oxide; a first EMI shielding layer comprising silver contacting the first layer comprising zinc oxide; a first layer comprising an oxide of Ni and/or Cr contacting the first EMI shielding layer comprising silver; a first metal oxide layer; a second layer of silicon nitride; a second layer comprising zinc oxide; a second EMI shielding layer comprising silver contacting the second layer comprising zinc oxide; a second layer comprising an oxide of Ni and/or Cr contacting the second EMI shielding layer comprising silver; a second metal oxide layer; a third layer of silicon nitride; a third layer comprising zinc oxide; a third EMI shielding layer comprising silver contacting the third layer comprising zinc oxide; a third layer comprising an oxide of Ni and/or Cr contacting the third EMI shielding layer comprising silver; a third metal oxide layer; a fourth layer of silicon nitride; a fourth layer comprising zinc oxide; a fourth EMI shielding layer comprising silver contacting the fourth layer comprising zinc oxide; a fourth layer comprising an oxide of Ni and/or Cr contacting the fourth EMI shielding layer comprising silver; and an overcoat layer comprising a transparent conducting oxide (TCO). The EMI filter has a sheet resistance of less than about 1 ohm. The overcoat layer comprising the TCO is about 30-40 nm thick. The TCO has a refractive index of about 1.95-2.05, more preferably about 2.0.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.